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PATH2220 > 5 - Red cells and Anaemia > Flashcards

5 - Red cells and Anaemia Flashcards

1
Q

Buffy coat

A

Leukocytes & platelets (<1% of total blood)

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2
Q

Red blood cells

A
  • Made in bone marrow
  • Small anuclear flexible biconcave disc shaped cells
  • Most numerous cell in blood
  • Generates energy through glycolytic pathway
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3
Q

How long do red blood cells last

A

120 days

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4
Q

Haem and globin

A
  • Haem: Mitochondria, contains iron
  • Globin: 4 polypeptide chains
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5
Q

Defects in globin

A

Thalassaemia and sickle cell disease

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6
Q

Blood cell production

A

Haemopoiesis

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7
Q

RBC production

A

Erythropoiesis

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8
Q

Erythropoiesis

A

Production of RBCs under influence of erythropoietin (EPO, produced in kidney)

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9
Q

Stages of RBC development in bone marrow

A
  • Cell becomes smaller
  • Nucleus matures (chromatin condensation)
  • Cytoplasm gains haemoglobin
  • Nucleus is extruded to produce mature RBC
  • Newly formed RBC = reticulocyte
  • RNA lost to become mature RBC
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10
Q

Erythropoietin (EPO)

A
  • Hormone that regulates red blood cell production
  • Produced in kidney
  • Stimulated by renal O2 tension caused by anaemia, low atmospheric O2, defective cardiac or pulmonary function
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11
Q

Requirements for erythropoiesis

A
  • Erythropoietin (EPO)
  • Metals (iron, cobalt)
  • Vitamins (B12, folate)
  • Amino acids
  • Other cytokines (IL3)
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12
Q

Iron

A
  • Only 5-10% of iron intake is absorbed
  • Binds in transferrin
  • Require 1-2mg / day
  • Excess stored in macrophages
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13
Q

Iron metabolism pathway

A

Duodenum and jejunum –> binds to transferrin –> bone marrow –> circulating haemoglobin –> Macrophages, liver, muscle myoepithelium

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14
Q

Vitamin B12 (Cobalamin)

A
  • Required for nuclear maturation
  • Dietary B12 combines with intrinsic factor (stomach)
  • IF-B12 complex attaches to receptors in ileum
  • Absorbed B12 binds to Transcobalamin II
  • B12 carried to marrow and liver
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15
Q

Where does B12 come from

A

Meat, eggs, milk

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16
Q

Where does folate come from

A

Fruit and vegetables

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17
Q

Folate

A
  • Required for nuclear maturation
  • Absorbed in upper small intestine
  • Small body stores (3-4 months)
  • Deficiencies result in anaemia (macrocytic)
18
Q

Red Blood Cell Membrane

A
  • Deformable & stabile (navigate small vessels)
  • Lipid bilayer with embedded proteins
  • Proteins for membrane elasticity
  • Proteins are embedded with lipids
19
Q

How do RBCs die

A
  • Removed in reticulo-endothelial system
  • Iron released and stored as ferritin
  • Globin chains are degraded to amino acids and returned to body pool
  • Haem broken down to bilirubin and excreted by liver
20
Q

Normal lifespan of RBcs

A

120 days

21
Q

Haemolysis

A

Reduced RBc lifespan/increased rate of RBC destruction

22
Q

Anaemia

A

A reduction in haemoglobin concentration below
normal range for age and gender of the individual

23
Q

Is anaemia a disease

A

No but rather a manifestation of another disease

24
Q

Clinical features of anaemia

A
  • Paleness
  • Lethargy
  • Shortness of breath
  • Tachycardia
  • Fainting
  • Low BP
25
Q

Causes of anaemia

A
  • Reduced bone marrow production of red cells
  • Increased blood loss (haemorrhage)
  • Increased RBC destruction (haemolysis)
26
Q

Primary causes of anaemia

A

Bone marrow failure

27
Q

Secondary causes of anaemia

A

Underlying problem reducing ability of the marrow to make red blood cells

28
Q

Primary causes of reduced bone marrow production of red cells leading to anaemia

A
  • Bone marrow failure (aplastic anaemia)
  • Red cell aplasia
  • Bone marrow dysfunction (myelodysplasia)
29
Q

Secondary causes of reduced bone marrow production of red cells leading to anaemia

A
  • Insufficient nutrients (iron, folate, B12, Erythropoietin)
  • Infection
  • Drugs
  • Marrow infiltration (Leukaemia, cancer)
30
Q

Iron deficiency causes

A
  • Poor iron intake / dietary deficiency
  • Poor iron absorption / malabsorption
  • Chronic blood loss:
  • Increased demand / iron utilisation
31
Q

B12 deficiency causes

A

poor absorption (pernicious anaemia)

32
Q

Folate deficiency

A

Poor diet, increased demands

33
Q

Megaloblastic anaemia

A
  • Caused by B-12 and folate deficiency
  • Larger cells with delay in development of nucleus
34
Q

Causes of haemorrhage leading to anaemia

A
  • Acute (Accident, injury, surgery)
  • Chronic (Malignancy, inherited platelet or bleeding disorder)
35
Q

Causes of increased RBC destruction leading to anaemia

A
  • Hereditary: Inherited defect of red cell membrane,
    red cell enzymes or globin chains
  • Acquired: sepsis, microorganisms, liver or kidney disease, fragmentation haemolysis
36
Q

Hereditary spherocytosis

A
  • Common cause of inherited anaemia
  • Defect of RBC membrane proteins
  • RBCs more rigid than normal
  • RBCs lack central pallor (spherocytes)
37
Q

Defect of RBC membrane proteins that causes hereditary spherocytosis

A

Structural proteins spectrin, actin and band 3

38
Q

Thalassaemia

A

Reduced production of a or b globin chains

39
Q

Structural haemoglobinopathies

A

Abnormal globin chain structure (e.g. sickle cell anaemia)

40
Q

Autoimmune haemolytic anaemia

A

An antibody directed against its own red blood cells. Caused by leukaemia and autoimmune diseases

41
Q

Haemolytic anaemia due to infections

A
  • Severe bacterial sepsis (causes RBCs to fragment)
  • Malaria (Parasite inside red cell causes lysis)
  • Clostridium welchii (Auto-antibody like haemolysis)

PATH2220 (33 decks)

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